Self-opening thread rolling head



July 27, 1965 W. KRUSE SELF-OPENING THREAD ROLLING HEAD Filed June 141961 L j I In ocular,-

By Au,

V I Attorneys,

United States Patent 1 3,196,650 SELF-OPENING THREAD ROLLING HEAD WernerKruse, Schwarzenbek, near Hamburg, Germany, assiguor to Wilhelm FettePrazisionswerkzeug-Fabrik, Hamburg, Germany Filed June 14, 1961, Ser.No. 117,179 Claims priority, application Germany, July 9, 1960,

31,265; Dec. 1, 1960, F 32,667

1 Claim. (Cl. 72-67) The invention relates to a self-opening threadrolling head and comprises a body member comprising threadformin-g rollsfreely mounted on eccentric pin elements arranged concentrically aroundthe workpiece and movable with a rocking motion into and out of theworking position, and a shank including a workpiece stop, these partsbeing axially displaceable but prevented from relative rotation by alocking device arranged between the body member and the shank, thisdevice being released when the workpiece strikes the stop.

In the known rolling heads of this kind it has been founddisadvantageous that a considerable mass must be moved both whenreleasing and also when closing the locking device so that a strongspring is required and hence, after engagement of the workpiece androtation of the displaceable part of the housing, there is anundesirably hard impact of this massive part of the housing against astop limiting the displacement. Also the reengagement of the rollinghead, which is effected by rotating the massive part of the housing byhand against the spring force, involves a considerable expenditure ofenergy.

According to the invention it is therefore proposed that one of the twomain parts of the head be further divided and that only a portion of thesaid one part, of comparatively small mass, has to be rotated foropening and closing the thread rolling head.

A self-opening thread rolling head according to the invention comprisestwo main sections one of which includes freely rotatable threading rollson eccentric spindles arranged concentrically around the workpiece bywhich the threading rolls may be moved into and out of the workingposition and the other consists of a shank portion comprising a hollowshaft and a workpiece stop, in which the section including the threadingrolls is axially slidable relative to the other section and includes tworelatively movable parts which, by their relative movement, move thethreading rolls towards and away from the working position and areadapted to be held by locking means in that position in which the rollsare in the workpiece engaging position.

FIG.1 shows a related form of die rolling head while FIG. 2 shows aconstruction example of my invention.

In the embodiment shown in FIG. 1 the rolling head comprises two mainsections, namely a shank section 3 and a body section 4 mounted upon theforward end of the shank section 3. The latter is adapted to be securedto a machine tool in a workpiece-engaging position and either the heador the workpiece is rotated to perform thread rolling. The shank section3 is hollow and houses a workstop 5 adapted to be engaged by the end ofa workpiece being threaded, for the purpose of effecting disengagementof the thread rolls as explained hereinafter.

The workstop 5 is screw threaded for a sleeve.6 at the rear end which isin threaded engagement with a screw threaded bore in the rear end of theshank part 3 and is adapted to be fastened after adjustment by means ofa lock nut 7. This adjustment permits the length of thread produced onthe workpiece to be adjusted.

The body section 4 comprises two relatively rotatable members includinga forward member 8 having a splined 3,196,650 Patented July 27, 1965"ice bore adapted to engage splines formed on the forward part of theshank 3 so that the member 8 can slide axially upon but cannot rotaterelatively to the shank 3. The second member of the body section 4comprises two cylindrical parts 9 and 10 which are adjustably coupled'one to the other by means of a spaced series of fastening studs 11.There may be three such studs spaced uniformly around the head and saidstuds are fixedly screwed into threaded apertures in the part 9 andtraverse arcuate slots in the part 10 so that a limited adjustmentbetween these parts is possible. The parts 9 and 10 may be fixed in theadjusted positions by means of nuts 12 on the studs 11 which clamp thepart 10 against the part 9. The part 9 may be provided with a circularboss-like portion accommodated within a recess in the rear face of themember 8 and these parts may be held in engagement by means of a ring 15fixed against an end face of a hub portion of the member 8 by means offastening screws 16, the outer edge of the ring 15 seating against astop face of the part 9.

Projecting outwardly from the part 9 is an operating lever 17 by whichthe parts 9 and 10 may be rotated as a unit relatively to the member 8for the purpose of closing the thread rolls into the working positionready for engagement with a workpiece to be threaded.

Located in front of the member 8 is a front plate 18 supported from themember 8 by means of spacer blocks 19 which are in threaded engagementwith the member 8, the front plate 18 being fastened to the spacerblocks 19 by means of countersunk fastening screws 20. The front plate18 is centrally apertured at 21 to admit a workpiece to be threaded.

Thread forming rolls 22 are rotatably accommodated upon eccentricspindles 23 by means of needle roller bearings 24. The eccentric members23 form part of carrier spindles 25 accommodated in apertures in thefront plate 18 and in the member 8.

The thread forming roll-s 22 are provided with a series of parallelperipheral thread forming grooves and the support spindles 25 are placedslightly obliquely to the centre axis of the head at an anglecorresponding to the mean helix angle of the thread to be rolled.

The rearmost end of each spindle 25 extends into a recess 26 formed inthe body member 8 and carries a projecting arm 27 to which a crank pin28 is fixed. This crank pin engages a slot 29 in the part 9 so thatrotation of the parts 9 and 10 relative to the member 8 performsrotation of the spindles 26 and thus causes the thread rolls 22 to moveinto or out of engagement with a workpiece entered through the aperture21 in the front plate 18.

A spiral spring 30 is provided within a housing formed within the bodypart 10 and is anchored at one end to said disc part 10 and at the otherend to the shank 3. Said spiral spring is designed so as to tend torotate the body parts 9 and 10 considered as a unit, relative to theforward member 8 of the body 4 in a direction which tends to move thethread rolls 22 away from the workpiece. The said spring is also adaptedto exert an axially directed force upon the body member 4 as a wholetending to force it along the shank part 3 to cause the body member tobe locked to the shank 3 by engagement of dogs 31 on the body part 10with mating dogs of a projecting flange 32 on the shank portion 3. Itwill be seen that these dogs serve to hold the disc parts 9 and 10 inrotary engagement with the shank 3 and that they are held engaged by theaxial force derived from the spring 30. While these conditions apply thethreading rolls 22 are locked in the working position and can be broughtinto operative rolling engagement with a workpiece presented at theaperture 21; relative rotation of the head and the workpiece performsprogressive rolling of a thread into the surface of the workpiece whichthus moves axially into the head until the workstop 5 is engaged.Thereupon locking engagement is released because the body section 4 as awhole moves in the axial direction upon the shank section '3 until thedogs 31 are disengaged from the dogs on the flange 32,whereupon thespring 30 rotates the parts 9 and 10 of the head relatively to themember 8 and consequently the arms 27 rotate the spindles so that theeccentric portions 23 thereof allow the thread rolls 22 to come out ofengagement with the workpiece.

In order to close the rolling head again the parts 9, 10 are moved backagainst the spring 30 by means of the hand lever 17 until the dogs 31are reengaged under the influence of the axial force component of thespring 30.

An alternative construction according to the invention is shown on FIG.2. In this case the shank section 3 is generally similar to FIG. 1 butisnot provided with a flange as at 32 in FIG. 1. The threading rolls 22are mounted by needle roller bearings 24 on eccentric portions 23 ofspindles 25. The latter are journalled at the outer end in -a frontplate 18 fastened to spacer blocks 19 by fixing'screws 20. In'thisembodiment, however, the body section 4 comprises two cylindrical partsI 35 and 36 which are rotarily adjustable (like the parts 9 and 10 ofFIG., 1) and are held fixed after adjustment by means of stemportions'37 of the spacer, blocks 19 which traverse apertures in thepart 35 and have threaded 4, these parts relatively. The rotation of thetoothed ring 41 causes rotation of the gear wheels 40 on spindles 25 todisengage the threading rolls 23 from the workpiece. After removal ofthe workpiece the head can be closed ready for the next thread rollingoperation by moving the hand lever 17 until dogs are again engaged, thuslocking the head in the working position.

If the rolling head is used as a rotating head and the workpiece isstationary, the opening action is the same without a special rollinghead being required. The rolling head according to the invention istherefore suitable without modification for machining a rotatingworkpiece or a stationary workpiece.

What I claim is:

A self-threading rolling head comprising a housing in which freelyrotatable threading rollers are concentrically arranged around the axisof said head, eccentric spindles supporting said rollers, gear memberson said spindles, a hollow shank portion adapted to support said headand for mounting in a machine tool, a central gear rotatably mounted onsaid shank portion and held against axial movement thereon, a stop rodadjustably mounted in said shank for engaging the end of a workpieceafter said threading rollers have moved a predetermined distance alongsaid workpiece, a clutch interposed betweenthe housing and said gear,said housing 7 being slidably splined on the end of said hollow shankend parts 38 which traverse arcuate slots in the part 36 and carry clampnuts 12' as in FIG. 1. Each spindle 25 carries a gear wheel 40 meshingwith a central toothed ring 41 forming part of a sleeve 42 which isrotatable upon the shank section 3 but is held from movement in theaxial direction by keeprings 43. Part of the sleeve 42 is accommodatedwith the body part 36 and is coupled permanently to or is integral witha collar 44 from which the operating lever 17 extends. One face of thecollar 44 and the adjacent face of the body part'36 are pro,- vided'withdisengageable driving dogs.

the shank section 3 so that these parts are relatively slidable in theaxial direction but cannot rotate mutual- 1y, Movement in the axialdirection occurs when a workpiecebeing threaded engages the workstop 5and such axial movement produces disengagement of the driving dogs 45which thus allow a spiral spring 30, arranged in the manner describedwith reference to FIG. 1, but con- The body part 35 has a splined boreseated upon splined end part of nected to the body part 36 and to thesleeve 42, to rotate and secured against rotation relative thereto andsaid References Cited'by the Examiner UNITED STATES PATENTS 2,651,224'9/53 Erdelyi 6 2,720,801 10/55 Eldelyi 806 2,909,078 10/59 Powell 80-63,058,196 10/62 Bour 806 WILLIAM J. STEPHENSON, Primary Examiner.

THOMAS E. BEALL, CHARLES W. LANHAM,

Examiners.

